Method of making solid propellant canister loaded rocket motor

Abstract

A canister loaded solid propellant rocket motor. The canisters are prepared separately and loaded with solid propellant whereby the scrap rate may be reduced after which they are installed in a monolithic case which affords stiffness continuity over the length of the rocket motor to prevent guidance system upsetting free play. In order to reduce the complexity of installation of the membrane seal assembly for each pulse, of a multi-pulse rocket motor the bulkhead therefor is manufactured integral with the case of the respective canister and becomes the forward closure thereof. For a multi-stage rocket motor, the monolithic case may be stepped and tapered, and the stages severable therefrom as they burn out by primer cord. A tight fit may be provided between a canister and the monolithic case by constructing the canister case to form a tight fit with the monolithic case at ambient temperature, lowering the temperature of the canister to a temperature which permits its insertion in the monolithic case, and allowing the canister to warm to ambient temperature.

What is claimed is: 
     
       1. A method of making a rocket motor comprising the steps of: a. providing a monolithic elongate generally cylindrical case;   b. providing at least two canisters each having an individual case and containing solid propellant material;   c. inserting each of the canisters in the monolithic case with the canister cases in engagement therewith;   d. attaching the individual canister cases to the monolithic case;   e. providing means within the monolithic case for igniting the solid propellant material; and   f. providing thrust nozzle means engaging the monolithic case.   
     
     
       2. A method according to claim 1 further comprising selecting at least one of the canisters to be constructed to form a tight fit with the monolithic case at ambient temperature, lowering the temperature of the at least one canister to a temperature which permits loading of the at least one canister in the monolithic case, inserting the at least one canister while at the lowered temperature in the monolithic case, and allowing the at least one canister to warm to ambient temperature thereby to expand and form a tight fit with the monolithic case. 
     
     
       3. A method according to claim 1 further comprising composing at least one of the canister cases of a composite of a resin impregnated fiber material coated with rubber. 
     
     
       4. A method according to claim 1 further comprising connecting the canisters together in end to end relation in the monolithic case, whereby of any two adjacent canisters the canister which is closest to the aft end of the monolithic case is the aft canister, and the other canister is the forward canister, providing a closure on an end portion of the forward canister to adjoin an end portion of the aft canister to preclude flow communication between the canisters, and providing means within the monolithic case for permitting flow communication substantially from the forward canister to the aft canister when a higher pressure is present in the forward canister than in the aft canister. 
     
     
       5. A method according to claim 1 further comprising connecting the canisters together in end to end relation in the monolithic case, whereby of any two adjacent canisters the canister which is closest to the aft end of the monolithic case is the aft canister, and the other canister is the forward canister, providing each of the canisters with a closed forward end portion and an open aft end portion to which a nozzle is attached in flow communication therewith and providing means for severing the aft canister from the monolithic case and releasing the aft canister therefrom after the solid propellant material in the aft canister has burned. 
     
     
       6. A method of making a rocket motor comprising the steps of: a. providing a monolithic elongate generally cylindrical case having a forward end and an aft end;   b. providing at least one canister having an individual case containing solid propellant material, the solid propellant material having a coaxial central aperture, and the canister being constructed to form a tight fit with the monolithic case at ambient temperature;   c. lowering the temperature of the canister to a temperature which permits inserting of the canister in the monolithic case;   d. inserting the canister in the monolithic case;   e. allowing the canister to warm to ambient temperature thereby to expand and form a tight fit with the monolithic case;   f. providing thrust nozzle means which engages the aft end of the monolithic case; and   g. providing means within the central aperture of the solid propellant material for igniting the solid propellant material.   
     
     
       7. A method according to claim 6 further comprising composing the canister case of a composite of a resin impregnated fiber material coated with rubber. 
     
     
       8. A method according to claim 6 further comprising bonding the individual canister case to the monolithic case. 
     
     
       9. A method according to claim 6 further comprising composing the monolithic case of a fibrous material selected from the group consisting of carbon fibrous material and graphite fibrous material, lowering the temperature of the monolithic case, and inserting the canister in the monolithic case when both the canister and the monolithic case are lowered in temperature. 
     
     
       10. A method according to claim 6 further comprising providing one or more additional canisters, each additional canister having an individual case containing solid propellant material, inserting the canisters together in end to end relation in the monolithic case, whereby of any two adjacent canisters the canister which is closest to the aft end of the monolithic case is the aft canister, and the other canister is the forward canister, providing a closure on an end portion of the forward canister to adjoin an end portion of the aft canister to preclude flow communication between the canisters, and providing means within the monolithic case for permitting flow communication substantially from the forward canister to the aft canister when a higher pressure is present in the forward canister than in the aft canister. 
     
     
       11. A method according to claim 6 further comprising providing one or more additional canisters, each additional canister having an individual case containing solid propellant material, inserting the canisters together in end to end relation in the monolithic case, whereby of any two adjacent canisters the canister which is closest to the aft end of the monolithic case is the aft canister, and the other canister is the forward canister, attaching the cases of the canisters to the monolithic case, providing each of the canisters with a closed forward end portion and an open aft end portion to which a nozzle is attached in flow communication therewith and providing means for severing the aft canister from the monolithic case and releasing the aft canister therefrom after the solid propellant material in the aft canister has burned. 
     
     
       12. A method of making a rocket motor comprising the steps of: a. providing a monolithic elongate generally cylindrical case having a forward end and an aft end;   b. providing at least two canisters each having an individual case and containing solid propellant material, the solid propellant material having a coaxial central aperture;   c. inserting each of the canisters in the monolithic case with the canister cases in engagement therewith;   d. attaching the individual canister cases to the monolithic case; and   e. providing means within the central aperture of the solid propellant material for igniting the solid propellant material; and   f. providing thrust nozzle means attached to the aft end of the monolithic case.